Means for feeding powdered fuel to furnaces



L. CLHARVEY AND H. s. BUCKLEY. MEANS FOR FEEDING POWDERED FUEL T0FURNACES. APPLICATION FILED AUG.5, I920. 1,389,828. PatentedSept. 6,1921.

' UNITED STATES PATENT ()FFICE.

LEONARD oHABLEsHaRvEY, or MALDEN, AND HARRY SYDNEY BUCKLEY, OF

ESTMINSTER, LONDON, ENGLAND.

'MEA NSFOR FEEDING POWDERE D FUEL TQ FURNACES.

To all whom it may concern: v y Be it knownthat we, LEONARD CHARLESHARVEY, of The Red House, Malden, Surrey, England, and HARRY SYDNEY-BUKLEY, of 25 Victoria street, Westminster, London, England, subjects ofthe King of Great Britain, have invented certain new and usefulImprovements in Means for Feeding Powdered Fuel to. Furnaces, of whichthe following is a specification. 1'

Our invention relates to apparatus for feeding powdered coal and likefuel to furnaces and has for its object to insure an efficientregulation and even feed over a wide range from a maximum fuel supplyto. a minimum supply. 1 I

Inordinary powdered coal feeders it is usual to employ a horizontalshaft'on which is mounted a screw .conveyer so that when the shaft isrotated at a variable speed powdered coal is fed to the delivery pipe inquantities corresponding with the speed of the conveyer. Thisarrangement, however, necessitates a variable speedmotor or other changespeed gear. e

In certain casesapparatus of this description has been rendered of theconstant speed type, variable feed being effected by means of a jaw orshutter at the regulation end of the feed-screw. V

The former type, namely, that fitted with variable speed motor, iscostly, on account of the special motor and switch gear required, andthe latter type, namely, theconstantspeed feeder, ,is at times notreliable due to packing of thecoal dust at the control jaws orshutters.r

The object of the present invention is, therefore, to eliminate thenecessity for, and the cost of, a variable speed electric motor and toso arrange for control of fuel feed that there can be no packing at thecontrol valve and that the feed-screw can be operated at a constantspeed. 7

To attain this end, instead of employing a horizontal feed-screw, as isthe general practice, we arrange this screw, which is adapted to berotated in any suitable manner, vertically inside a barrel or tube andwe introduce the fuel into this barrel, near the lower end thereof froma hopper having vertical sides and an inclined bottom, and raise thefuel into a box at the upper end. On either Specification of LettersPatent.

Patented Sept. 6, 1921.

Application filed August 5, 1920. Serial No. 401,341.

side of this feed and also connectedto the box are fixed respectively afuel delivery pipe, to connect up with the air supply for introductionof the fuel to the burner, and a pipe for the returnof the excess offuel supplied by the' central feed screw, the surplus fuel beingreturned to the lower end of the latter, the said lower end of the feedscrew and of the barrel inclosing it being preferably made of slightlylarger diameter than themain part thereof. To controlthe distribution ofthe fuel, fed to the box by the feed-screw to the delivery pipe and tothe by-pass pipe the box is furnished with a swing valve which is soarranged that the supply can be entirely out ed to the delivery pipe oropened up suficiently to allow the required amount of fuel to pass, orso that the whole quantity of fuel fed by the screw feeder will bedirected into the supply pipe.

To enable the invention to be fully understood we will describe the sameby reference to the accompanying drawing, in which I Figure 1 is asectional elevation of fuel feeding apparatus constructed in accordancewith the invention.

i Fig. 2 is a sectional elevation at right angles to Fig. 1, and

Fig. 3 is a vertical section of the valvebox on the line 33, Fig. 2.

a indicates the hopper containing the powdered fuel, the said hopperhaving vertical sides and aninclined bottom 6. c is the feed-screw whichis mounted vertically so that it can rotate in the bearings d in the.

barrel or feed-tube e. f is a worm driving gear by means of which thelower end of the feed-screw c is revolved; g is an opening near thelower part of the barrel or tube 6 by means of which the interior of thesaid tube is placed in connection with the bottom of the hopper a sothat powdered fuel is fed by gravity from the said hopper into the tube.n is the valve box into which the upper end of the feed-tube 6 opens and2' and j are respectively the delivery pipe and the by-pass pipe whichopen from the valvebox on either side of the feed-tube e. The former,that is to say the delivery pipe '5, conveys the fuel from the box tothe burner, while the latter, that is to say the by-pass pipe isconnected at its lower end to the lower end of the feed-tube e, which tofacilitate the reception of the fuel which isby-passed is made of largerdiameter than the rest of the tubes, the screw 0 being alsomadecorrespondingly larger to fit therein.

71 is the valve fitted within the box it, the said valve being carriedupon the spindle Z which is mounted in bearings m in the box immediatelyabove the center of the feed tube e and has keyed upon it, externally ofthe box, the toothed quadrant n with which gears the worm 0 designed tobe rotated in the bearings p by the hard wheel g."

The apparatus operates as follows, thatis to say powdered fuel from thehopper a passes through the aperture 9 into the feedtube e up which itis then forced, in the direction of the arrow 1 Fig. 2, by the rotat ingfeed-screw c. On reaching the upper end of the tube 6 the fuel entersthe box it, its distribution being controlled bygthe valve 70; When'thevalve is in its central position,

shown in Fig. 3, the fuel is directed in more i i or less equalproportions in the directionof the arrows 2 and 3'respectively into thedelivery pipe z' and the by-pass pipe 7' whence it is delivered asindicated respectively by the arrows 4: to the burner and by the arrow 5to the lower part of the feed barrel or tube 6'. As will be'understoodthe valve 70 may ing provided with delivery apertures 'on opposite sidesof the feed tube, a delivery tube connected with one of said apertures,a

by-pass tube connected with the other of said apertures for returningthe fuel to be re-fed by the, feed tube, and an adjustable valve in saidchamber pivoted substantially in line with the axis of the feed screw,and

adapted to close communication between the feed tube andeither of saidapertures, and

means for adjusting said valve to either of.

said positions or any desired intermediate position. M V i 2. Apparatusfor feeding powdered fuel to furnaces comprising a hopper, averticallydisposed feed tube communicating with the hopper at apoint between theends of said feed tubeand having. a portion extending below saidcommunication with the hopper,

a rotatable feed screw extending through said feed tube, a chamber attheupper end of the feed tubecommunicating therewith and provided withdelivery apertures on opposite sides of the feed tube, a delivery tube 7connected with one of said apertures, a bypass tube connected to theother of said apertures and connected-with thelower end of the feed tubebelow its-connection with the hopper, and an adjustable cvalve'in saidchamber pivoted at a point in line with the axis of the feed screw, andadapted to stand in alinement therewith and to be moved in eitherdirection to close communication between the feed tube and either ofsaid delivery apertures.

3. Apparatus for feeding powdered fuel to furnaces comprlslng a hopper,a vertically disposed-feed tube having an aperture in its sidecommunicating with said hopper and having a portion extending below saidcommunicating aperture, the lower portion of said feed tube being ofgreater diameter than the-upper portion, a feed screw extendinglongitudinally through said feed 7 tube and having a portion-of largerdiameter at itslower end, a, chamber communicatlng with the feed tube atits upper end, and provided with delivery apertures'in its bottomwall'on opposite sides of the feed tube,

a delivery tube connected with one o'f'saidapertures, a bypass tubeconnected at its upper end with the other of saidapertures and extendingdownward parallel withthe feed tube and communicatingtherewith .adjacent to the bottom of the feed tube and an adjustable, verticallydisposed valve in said chamber pivotally' mounted centrally above thefeed tube and movablein opposite directions to positions in which one orthe other of said delivery apertures is closed. f V LEONARD CHARLESHARVEY. HARRY SYDNEY, BUCKLEY.

